Longshot has released version 1.3 of the Amstrad CPC CRTC Compendium (beware, the english version isn't definitive, only the french one is actually) which is a documentation about the CRTC 6845 (and some others circuits). Note that the CRTC is a generic component used in several computers including the IBM PC.

As seen on CPCRulez, the AMSpiriT emulator by Dmanu78 is respecting by a great margin the SHAKER tests by Longshot than other emulators. SHAKER is a program designed to run on CPC machines produced by AMSTRAD in the 80s-90s. The objective of this program is to carry out extensive tests on the video circuits of this machine. These video circuits are the GATE ARRAY and the CRTC 6845. AMSTRAD produced several series of GATE ARRAY and used CRTC models produced by different manufacturers (HITACHI, MOTOROLA, UMC, AMSTRAD). This has been causing compatibility problems on operations that exceed the functional specifications of these circuits. The identified CRTCs are numbered from 0 to 4.

So AMSpiriT is better especially if you like to see Amstrad CPC demos, and can't be bad either for games. I don't have the time to test extensively all Amstrad CPC games, but for sure I will take time during the Benediction Coding Party #2 to use it.